voice-cat/clients/windows/VoiceCat.App/Forms/ServerIdentityDialog.cs

using VoiceCat.Interop;

namespace VoiceCat.App.Forms;

/// <summary>
/// TOFU server-identity confirmation. Shown only for VcTofuStatus.FirstConnect/Mismatch
/// — never Matched (that's the silent-success "subsequent connects verify the pin" path
/// docs/security.md describes; showing a dialog on every routine reconnect would be exactly
/// the "overly chatty" experience this project avoids elsewhere too).
/// DialogResult.OK = accept (and the caller should call ConfirmServerIdentity(true) and, for
/// FirstConnect/Mismatch, the core persists the new pin); DialogResult.Cancel = reject.
/// </summary>
public partial class ServerIdentityDialog : Form
{
    public ServerIdentityDialog(VcTofuStatus status, string certFingerprintHex, string identityDisplayHex)
    {
        InitializeComponent();

        string formattedCertFp = FormatFingerprint(certFingerprintHex);
        string formattedIdentityFp = string.IsNullOrEmpty(identityDisplayHex)
            ? "(not yet available)"
            : FormatFingerprint(identityDisplayHex);

        if (status == VcTofuStatus.Mismatch)
        {
            Text = "WARNING: Server identity changed";
            lblWarning.Text =
                "WARNING: This server's identity has CHANGED since you last connected.\r\n\r\n" +
                "This could mean the server was reinstalled, OR that someone is intercepting " +
                "your connection. If you did not expect this server's identity to change, " +
                "choose Cancel.";
            lblFingerprint.Text = $"New certificate fingerprint:\r\n{formattedCertFp}\r\n\r\n" +
                                   $"Server also identifies as:\r\n{formattedIdentityFp}";
            btnAccept.Text = "&Trust the new identity anyway";
        }
        else
        {
            Text = "New server — verify identity";
            lblWarning.Text =
                "You have not connected to this server before. If you have verified its " +
                "fingerprint with the server operator through another channel, choose Trust " +
                "and connect. Otherwise, choose Cancel.";
            lblFingerprint.Text = $"Certificate fingerprint:\r\n{formattedCertFp}\r\n\r\n" +
                                   $"Server also identifies as:\r\n{formattedIdentityFp}";
            btnAccept.Text = "&Trust and connect";
        }
    }

    protected override void OnShown(EventArgs e)
    {
        base.OnShown(e);
        // Force a screen reader to read the warning text immediately on dialog activation,
        // rather than landing focus straight on a button and silently skipping it.
        lblWarning.Focus();
    }

    private static string FormatFingerprint(string hex)
    {
        // Groups of 4 hex chars, like a product key — easier to read/dictate/compare than one
        // unbroken 64-character string.
        var groups = new List<string>();
        for (int i = 0; i < hex.Length; i += 4)
            groups.Add(hex.Substring(i, Math.Min(4, hex.Length - i)));
        return string.Join(' ', groups);
    }
}